This invention relates generally to high speed weaving looms, and particularly to weaving looms which are operated at speeds in the range of at least 400 picks per minute and an improvement thereto which is directed to the elimination or minimization of the troublesome vibrations occurring therein.
There has been developed in recent years high speed weaving looms of the type which incorporate the "short sword system." The term "short sword system" refers to a loom in which the rocker shaft about which the lay or lay plate is oscillated in close proximity to the lay itself and the main crankshaft of the loom. Thus, the axis about which the lay rocks is considerably closer to the lay than is the case in the "long sword system" in which the axis about which the lay oscillates is near the floor.
The short sword system development which was developed primarily to increase speeds also results in some reduction in the vibrations attendant to the oscillatory movement of the lay when a longer pivot arm is utilized. However, because of the extremely high speeds of the mass of the lay oscillating about the rocker shaft, there are still generated undesirable and, in fact unacceptable, vibrations.
Vibrations caused by the reciprocatory movement of the lay in general, have been recognized in the prior art. For example, attempts to reduce such vibrations by utilizing counterbalancing concepts are disclosed in U.S. Pat. No. 4,076,048 to Bolleter et al and U.S. Pat. No. 3,955,603 to Martelli. The simplest approach to counterbalancing the effects of an oscillating mass on a moment arm is to apply an identical mass on an opposite moment arm. The counterbalancing approach disclosed and described in the Martelli U.S. Pat. No. 3,955,603 is in the environment of a long sword system. As there is no clearance room beneath the axis of rotation, a different approach had to be adopted. Thus, in Martelli the connecting rod which extends between the main crankshaft and the rocker shaft is elongated and a mass is added to the end of the connecting rod on the opposite side of the crankshaft from the rocker shaft. While this may help some, the mass, so located, is really not in the proper location to fully offset the vibrations.
The approach described in the Bolleter et al U.S. Pat. No. 4,076,048, while utilized on a short sword system, involves substantially a re-design of the rocker shaft. The redesign approach was adopted, because Bolleter et al was attempting to incorporate an offsetting mass without any additional weight being added which would result in greater energy usage. In order to accomplish this goal, first of all, the Bolleter rocker shaft is separated into several separate, colinear shaft portions which are each coupled to the main shaft by a cam follower, so that the shaft portions reciprocate. The shaft portions are then connected to a balance weight in the form of another weighted shaft portion(s) by a plurality of spaced coupling members. A lever, which surrounds the rocker shaft then supports the lay in the proper position, so that as the rocker shaft reciprocates, it causes the balance weight shaft to reciprocate in an arcuate path below and the lay to reciprocate in an arcuate path thereabove. While this may be somewhat effective, it is tremendously expensive to implement, introduces complicating factors to conventional lay oscillatory theories, and from a practiced standpoint, cannot be introduced as a retrofit for existing installations.
By comparison, and in accordance with the present invention, the undesirable vibrations are eliminated, or at least minimized, by means of a simple counterweight which is suspended from each end of the rocker shaft of conventional high speed, short sword loom systems diametrically opposite the lay. The counterweight is of such size and is so positioned as to shift the center of gravity of the oscillatory elements to a position substantially coincident with the center of gravity of the rocker shaft with a minimum of structural changes to the conventional loom configuration. This approach can be incorporated as a retrofit for existing installations, and more importantly, has been found to be completely satisfactory in substantially eliminating all vibrations in high speed looms, even air jet looms.
More specifically, a steel, lead, or other heavy metallic plate is suspended beneath each end of the rocker shaft, each of such plates being supported by two or more suspension brackets. Thus, the weight is positioned in the appropriate location to most effectively offset the vibrations which normally occur as a result of the oscillatory motion of the lay the reed, and such weft directing components as may be mounted on the lay plate as auxiliary air nozzles and the like. The counterbalancing effect of the present invention is achieved in the simplest, and thus the most efficient manner conceivable.
It is therefore an object of the present invention to nullify to the maximum extent possible the undesirable, oscillating lay induced vibrations occurring in a short sword weaving loom in the simplest and most expeditious manner possible.
It is another object of the present invention to minimize or nullify vibrations of the type described by suspending an equal and offsetting counterbalance on the opposite side of the rocker shaft axis from the vibration creating components which include the lay, loom reed, and weft directing components.